Even now, sorting product packages, boxing of them, putting them on shelves and taking them out of the shelves are performed manually in many cases. It is desired that these operations be automatically performed by machines. However, the product packages are not necessarily arranged in order on product shelves or in cardboard boxes. Some of the product packages may be stacked neatly, and some may not. In this state, each package product cannot be easily identified though this identification is required for automation.
An arrangement detection apparatus uses matching technology for two dimensional images, which utilizes difference information between a template image of an object and an acquired image. However, this arrangement detection apparatus does not use depth information and does not ensure accurate detection of individual objects. If objects of the same shape are arranged with no gap between them, no method is available to detect how each object is arranged.